The present invention relates to the field of dental devices and in particular, to tooth inserts for positioning between teeth.
In dentistry, teeth which are subject to decay are typically drilled or otherwise prepared by removing the decayed tooth material. This leaves an aperture, slot or other void in the tooth which is then filled with composite resin or other filling material. A class 2 filling is a dental procedure in which a decayed area of a tooth along a portion of one or both proximal surfaces is prepared and filled. The proximal surfaces of a tooth are those surfaces of the tooth that face the surface of an adjacent tooth. The proximal surface that faces an adjacent tooth toward the front of the dental arch may be referred to as the mesial proximal surface. The proximal surface that faces an adjacent tooth toward the back of the dental arch may be referred to as the distal proximal surface.
When dentists perform class 2 cavity preparations, they typically insert a temporary substrate adjacent to the cavity preparation to contain and shape the filling material. The temporary substrate that dentists have traditionally used is an elongated band called a matrix band. Matrix bands are typically formed from a flexible metal strip, such as a stainless steel strip about xc2xc inch wide and about 0.001 to 0.002 inch thick. One example of a matrix band is disclosed in U.S. Pat. No. 2,591,744 to Tofflemire.
Before being placed in the patient""s mouth, a matrix band usually is placed in a retaining device or other type of tool to position and tighten the band around the tooth so that it at least partially surrounds and conforms closely to the shape of the tooth. Examples of such devices are the Tofflemire retainer disclosed in U.S. Pat. No. 2,538,486 to Tofflemire and a windable cylindrical coil disclosed in U.S. Pat. No. 4,523,909 to Lazarus.
When restoring a tooth, it is important to achieve a closed contact between the restored surface and the adjacent tooth to prevent food from becoming impacted between the teeth and causing periodontal disease. One problem with conventional matrix bands is that when they are removed from a class 2 filling made with composite filling material, a gap often remains between the filled tooth and the adjacent tooth. The gap is typically roughly as wide as the thickness of the matrix band which was used in the filling.
To solve the problem of open contacts in class 2 composite fillings, dentists sometimes employ special techniques and tools to wedge apart or otherwise force apart the adjacent teeth during the filling process. After the filling material is cured, the device separating the adjacent teeth is removed to permit the teeth to spring back together, hopefully just far enough to leave a fully closed contact between the teeth. One specific technique involves the use of mechanical wedges driven in place by finger pressure between adjacent teeth at a location well below the contact area. Another known technique involves forcefully separating the teeth by use of a metal ring (known as a bitine ring) which applies powerful forces inward between the teeth at a location just beneath where they meet.
However, such forceful separation of adjacent teeth may be difficult for the dentist and uncomfortable for the patient. Another disadvantage of using techniques involving forceful separation of adjacent teeth is that the extent to which the teeth will spring back together following the procedure is somewhat unpredictable. Moreover, in a class 2 filling in which a matrix band is positioned around a tooth having a prepared proximal surface (i.e., a proximal surface requiring restoration) and an intact proximal surface (i.e., a proximal surface not requiring restoration), the thickness of the band between the intact proximal surface and an adjacent tooth tends to push, or drive, the tooth being filled toward the tooth adjacent the prepared surface. Consequently, additional force is required to adequately wedge apart the adjacent teeth on the side of the prepared surface for packing the filling material into the cavity.
A recent attempt to solve the problem of open contacts that requires less forceful separation of adjacent teeth is to use matrix bands having areas of reduced thickness for insertion between the proximal surfaces of adjacent teeth. However, if a tooth has only one prepared proximal surface, matrix bands of this type can be difficult to place between the tight intact interproximal contact (i.e., the contact between the intact proximal surface not requiring restoration and an adjacent tooth) because the band is very thin and pliable. Such a band may buckle or tear and may not slide through the intact interproximal contact.
Shorter matrix bands are known which provide a form to enclose the proximal surface requiring restoration but are not long enough to completely encircle the tooth, and therefore do not require insertion between the intact interproximal contact. One popular version of a shorter band is known as a sectional matrix. Another version is a pre-formed, C-shaped band disclosed in U.S. Pat. No. 4,704,087 to Dragan. However, such short matrix bands are undesirable in that they are difficult to tighten around a tooth and maintain a close contact between the inner surface of the band and the outer contour of the prepared tooth to avoid the formation of a ledge at the gingival edge of the filling.
A need exists for an improved tooth insert for use in restoring a tooth having one proximal surface requiring restoration and one intact proximal surface.
According to one aspect of the disclosure, a tooth insert is provided for engaging around a first tooth having a prepared proximal surface requiring restoration adjacent to a second tooth and an intact proximal surface adjacent to a third tooth at the opposite side of the first tooth from the second tooth. The tooth insert in one form comprises an elongated band having first and second spaced apart central portions. The central portions are positioned so that when the band is wrapped around the first tooth, the first central portion is positioned between the prepared proximal surface of the first tooth and the second tooth and the second central portion is positioned between the intact proximal surface of the first tooth and the third tooth. An aperture is formed in the second central portion to permit at least partial interproximal contact between the first and third tooth through the aperture to minimize separation between the first and third teeth caused by the thickness of the band.
In a disclosed embodiment, the aperture is dimensioned to be larger than the area occupied by the natural, intact interproximal contact of the first and third teeth to eliminate separation therebetween caused by the thickness of the band when the band is positioned around the first tooth. Consequently, when the band is in place around the first tooth for filling, the band does not cause the first tooth to move toward the second tooth, which is adjacent to the prepared cavity. As a result, additional wedging or separation between the prepared proximal surface and the second tooth is not required to permit packing of filling material into the cavity.
The band may include an edge portion of reduced thickness extending along the gingival edge of the band under the aperture to facilitate insertion of the band between the intact interproximal contact of the first and third teeth. The band also may include a projection extending in the occlusal direction above the aperture. The projection adds rigidity to the portion of the band to be inserted between the intact interproximal contact. The projection also provides a convenient location on which a dentist can apply finger pressure to push the band through the intact interproximal contact area. In addition, the first central portion of the band, which is adjacent the prepared cavity when the band is installed, may have a thickness that is less than the thickness of the band.
The present invention is directed toward new and non-obvious aspects and features of a tooth insert, both alone and in various combinations and sub-combinations with one another. In addition, the invention is directed toward new and non-obvious method acts or steps relating to producing a tooth insert, both alone and in combination with one another. These new and non-obvious aspects, features, acts and/or steps and combinations and sub-combinations thereof are set forth in the claims below.